Amir al-Sha'bi (may Allah have mercy on him) said: Someone who was present with the Prophet (peace and blessings be upon him) told me that he (peace and blessings be upon him) came to an isolated grave, then he (peace and blessings be upon him) lined them (the Companions) up in rows and said four takbirs. Sulayman al-Shaybani said: I asked al-Sha'bi: O Abu Amr, who narrated this hadith to you? He said: Sayyiduna Ibn Abbas (may Allah be pleased with them both).
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12528